1 . Field of the Invention
The invention relates to a grinding apparatus for pointing electrodes for TIG welding, the apparatus including a rotatable grinding disc and a holding device for the electrode as well as a feed device for feeding the electrode toward the grinding disc, wherein the holding device and the grinding disc are adapted to be adjusted relative to each other so that the longitudinal direction of the electrode forms a desired angle with the plane of the grinding disc.
2. The Prior Art
In TIG welding it is important to keep the electrode pointed to achieve a good an stable arc. This is decisive for the achievement of a good weld. However, the tip is worn by the arc itself, just as particles may splash from the molten pool onto the electrode, and it also happens that the electrode can be accidentally dipped down into the molten pool, in particular when the operator is welding in an awkward position.
Special grinding machines have been developed for the grinding of the electrodes, which are typically of wolf-ram. These machines, however, are cumbersome in use, which means that the electrodes are not maintained to the necessary extent, resulting in welds of inferior quality. For example, in one of the known machines the electrodes have to be mounted in a special holder, and there are several different holders adapted to electrode diameters. The holder with the electrode then has to be mounted in the machine.
DE 33 05 149 describes a grinding machine which may be used for the grinding of wolfram electrodes, which are secured in a holder that is moved with threaded spindles until the electrode tip makes contact with the grinding disc. As the spindles have to be screwed both forwards and backwards for each electrode to be pointed, the grinding machine is very slow in use.
The object of the invention is to provide a grinding apparatus which is simple in use, and which is simultaneously faster to load and unload.
This is achieved by an apparatus according to the invention, wherein the feed device includes a drivable roller which is adapted to press the electrode laterally toward the grinding disc, and wherein the axis of rotation of the roller forms an angle with the longitudinal axis of the electrode, so that the roller by rotation moves the electrode forwards toward the grinding disc.
The apparatus is simple in use, as, in the insertion position, the electrode is merely to be placed on the carrier face of the first element, following which the two elements are mutually displaced to secure the electrode. After pointing, the electrode is released merely by returning the carrier face of the first element to the insertion position. Guide faces facilitating the positioning of the electrode may be provided in connection with the carrier face on the first element. Securing of the electrode may involve fixing, where the two elements as a unit with the fixed electrode are fed toward the grinding disc in the desired angular position. Also loose securing may be involved, said electrode being axially movable so that it may be moved toward the grinding disc.
The roller may rotate about a first centre of rotation, said roller having a shaft which is moved in the cylinder of an enclosing guide. This ensures stable rotation of the roller.
The carrier face for the electrode may advantageously be formed by a longitudinal plate member which is mounted rotatably about the first centre of rotation, said plate member having an edge in its longitudinal direction for carrying the electrode during insertion and loading of the grinding apparatus. This ensures simple insertion of the electrode.
The roller may be made of preferably an elastomeric material which is adapted to press the electrode laterally toward the grinding disc, and the axis of rotation of the roller may form such an angle with the longitudinal axis of the electrode that the roller by rotation moves the electrode toward the grinding disc. It has been found that the roller just has to be inclined slightly for it to carry the electrode forwards toward the side of the grinding disc.
The grinding apparatus may contain a plate member with a carrier face which cooperates with a rear member with a longitudinal downwardly facing engagement face for securing the electrode in a lateral direction in a grinding position. This ensures effective securing of the electrode in the grinding position.
The grinding apparatus may be formed with an edge on the plate member which cooperates with a first notch for securing the electrode in the grinding position, said first notch being formed in a side plate, said side plate likewise having a second notch for locking the plate member in an operative position. The grinding apparatus may hereby be locked in the grinding position, so that the operator just has to ensure rotation of the electrode during grinding.
The grinding apparatus may contain a guide cylinder which is swingably mounted on the plate member and spring-loaded to engage it. During grinding, the electrode may hereby automatically be pushed against the roller which pushes the electrode against the grinding disc.
The grinding apparatus may be constructed so that the rear edge of the plate member serves as a stop for rotation of the cylinder member in cooperation with a fixed part in the apparatus. The movement of an insertion handle may hereby be limited, thereby optimizing the operation of the grinding apparatus.
A possible embodiment of the apparatus according to the invention will be described more fully with reference to the accompanying drawings.